It turned out that I was only about halfway in separating the components when I made my last post. It turned out there was a deep vein of epoxy still binding tang to wood and the silver foil sleeve. An eight hour soak in methyl ethyl ketone (MEK) would penetrate and soften about a millimeter thickness of the epoxy with further softening not observed from a longer soak. The weakened epoxy could then be scraped away with a dissecting needle and the cycle repeated for days. The old tar-like material, still tacky in places, but mostly dried, originally securing the blade in place was much more vulnerable to the MEK and the tang finally released. Soaking of the wood and silver continued until I could no longer reach the remaining epoxy between the silver and the wood. At this point I gave it a bit of time to dry and applied heat with a kitchen stove-top burner. The MEK residue still lit a couple of times. Finally the remaining epoxy failed and I got the silver tube free from the remains of the shaft. The silver tube went off to Battara and I suspect he had been expecting something more substantial - this silver was really more a silver foil - thicker than kitchen aluminum foil but not nearly as thick as the wall of a typical food can. The torn areas were a bit too distorted for recovery, so we decided to sacrifice about an inch of this area as the design was in a helix and repeated.
In due course I hope to get this on a pole, leaving a hidden backing of copper seamless tube beneath the silver sleeve. It is nice to have gotten the wood out reasonably intact to see how the blade was mounted - the tarry substance was doing most of the work - unfortunately, the wood is unlikely to provide
further clues of its origin.